x86: h264qpel: Move stray comment to the right spot and clarify it

libavcodec/x86/dsputil_mmx.c

@@ -2181,8 +2181,6 @@ static void dsputil_init_avx(DSPContext *c, AVCodecContext *avctx, int mm_flags)
     const int bit_depth = avctx->bits_per_raw_sample;
 
     if (bit_depth == 10) {
-        // AVX implies !cache64.
-        // TODO: Port cache(32|64) detection from x264.
         if (CONFIG_H264CHROMA) {
             c->put_h264_chroma_pixels_tab[0] = ff_put_h264_chroma_mc8_10_avx;
             c->avg_h264_chroma_pixels_tab[0] = ff_avg_h264_chroma_mc8_10_avx;

libavcodec/x86/h264_qpel.c

@@ -611,6 +611,10 @@ void ff_h264qpel_init_x86(H264QpelContext *c, int bit_depth)
     }
 
     if (EXTERNAL_AVX(mm_flags)) {
+        /* AVX implies 64 byte cache lines without the need to avoid unaligned
+         * memory accesses that cross the boundary between two cache lines.
+         * TODO: Port X264_CPU_CACHELINE_32/64 detection from x264 to avoid
+         * having to treat SSE2 functions with such properties as AVX. */
         if (bit_depth == 10) {
             H264_QPEL_FUNCS_10(1, 0, sse2);
             H264_QPEL_FUNCS_10(2, 0, sse2);